title: Aromaticity and activation strain analysis of [3 + 2] cycloaddition reactions between group 14 heteroallenes and triple bonds.
abstract: We have computationally explored the trend in reactivity of [3 + 2] cycloaddition reactions between H(2)E=C=PH and HC≡CH as the terminal position in the phosphaallene is varied along E = C, Si, Ge, Sn, Pb. The reaction barrier drops significantly from E = C (nearly 50 kcal/mol) to E = Si-Pb (ca. 20 kcal/mol). Activation strain analyses tie this trend to a reduction in activation strain in the heavier phosphaallene analogues which, in contrast to the parent compound H(2)C=C=PH, do already possess the bent geometry required in the TS.
authors.affiliation: Departamento de Química Orgánica, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain. israel@quim.ucm.es
authors.forename: Israel
authors.initials: I
authors.lastname: Fernández
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Cossío
authors.forename: F Matthias
authors.initials: FM
authors.lastname: Bickelhaupt